Visual programming environments will never succeed, as long as the goal is to be "better than text". In the current attempts, one writes code with shapes and connecting lines instead of with letters and punctuation, but the linguistic concepts behind the code are still recognizable and readable. The catch is that this turns out to be a far less efficient way to encode language than text is: it's harder to write, and it's harder to read, so people inevitably gravitate back toward text, and the visual aspect is forgotten.
Does this mean visual programming is doomed? Not necessarily, but it needs to refocus its goal on something much more radical than attempts to date have really done. Current attempts try to be "better than text," and even the article here seems to advocate this approach. Instead, they need to focus on being better than language. This is where visual programming really has potential: rather than trying to replicate what text can do, it needs to focus on what text can't do.
How would something like this work? I haven't the faintest idea. I literally cannot imagine what it would be like to code without language. But a lot of concepts have emerged, even just during my own lifetime, that I could not have imagined before seeing them. Perhaps this is the same.
So there's my challenge to the "visual programming" folks. Express to me the nature of (and a possible solution to) some moderately complex problem, without using language of any sort. Manage this, and your task is largely finished: all that remains is to come up with a visual editor for encoding information in your chosen method. Do this, and you will have your revolution.